摘要:

Abstract31P NMR was used to study the systemic effects of a tumor on a host organism by monitoring the phosphate metabolite content in freshly excised mouse liver at 0–4°C and in ethanolic liver extracts of animals suffering from La, L1210 and P388 leukemias and Ehrlich ascites tumor (EAT). The progression of murine leukemia is characterized by increases in the intensities of the resonances of Piand phosphomonoesters (PME), in particular, phosphorylethanolamine, in liver; phosphodiester (PDE) signals increase two‐ to four‐fold during the period of rapid tumor growth and decline to undetectable levels in the terminal stage. There were no reliable alterations detected in the ATP content and intracellular pH throughout the course of the leukemia. The kinetics of intracellular phosphates are similar in various kinds of leukemia but quite different in EAT. The reduction of inoculum causes the appearance of maxima in the Piand PME profiles in the latent period of La leukemia, but the profiles of liver PDE considered from the end of the latent period are independent of inoculum. Possible mechanisms for the changes in PDE concentrations and their biochemical role are discussed. NMR spectroscopy of liver may be used to indirectly monitor the progression of tumors unavailable for direct NMR

ISSN:0952-3480    

DOI:10.1002/nbm.1940050302

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractIn vivo31P magnetic resonance spectroscopy (MRS) was undertaken in 28 healthy adult individuals and 32 patients with hepatic malignancies of varying histology, using chemical shift imaging techniques. The mean peak area ratio (total range) of phosphomonoester (PME) to phosphodiester (PDE) in the health adult group was 0.23 (0.15–0.41). The mean (total range) PME/PDE ratio of the total patient group was 0.68 (0.15–2.38), which was significantly elevated (P<0.001) compared to the mean of the healthy adult group. Liver biopsies, obtained at operation, were analysed using high‐fieldin vitroMRS techniques in order to identify the contributions of aqueous‐soluble metabolites to the multicomponent PME and PDEin vivosignals. Concentrations of phosphorylethanolamine (PE), phosphorylcholine (PC), glycerophosphorylethanolamine (GPE) and glycerophosphorylcholine (GPC) were measured. Thein vitrospectrum of six samples of liver of normal histological appearance all showed a similar pattern of PE, PC, GPE and GPC. Thein vitrospectrum of seven liver tumours of differing histology all showed an increase in PE and PC signals and a decrease in GPC and GPE signals. Thein vitroresults were compared within vivofindings in five patients. The increase in PME/PDE observedin vivorepresented, in part, an increase in PE and PC in the PME region and a decrease in GPE and GPC in the PDE

ISSN:0952-3480    

DOI:10.1002/nbm.1940050303

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractIn vivo19F NMR at 4.7 T has shown that the biphasic elimination of the vapor anesthetic isoflurane from rat brain is ca 15% slower in old (23‐24 months) animals compared with young (5–6 months) animals. The fast kinetic component has a t1/2of ca 7–9 min and the slow event, 100–115 min. Gas chromatographic measurement of arterial blood elimination displays age attenuation to the same extent, although a monophasic kinetic process (6–7 min). The slow wash‐out from brain is thought to involve elimination from intracranial fatty tissue as postulated by others in rabbit brain. Longitudinal relaxation time measurements show monoexponential recovery and essentially identical values for young (1.09+0.11 s) and old (1.04±0.09s) animals. For dipalmitoylphosphatidylcholine vesicles the monoexponential recovery also suggests rapidly exchanging averaged homogeneous lipid environments for the anesthetic, but the longer T1s (2.75±0.25 s) imply less restricted mobility compared with brain. Single T2values were obtainedin vivo, indicating either a single compartment or rapid exchange between multiple environments. These measurements were inconsistent, undoubtedly as a result of B1inhomogeneity. The age‐attenuated elimination kinetics for isoflurane are consistent with poorer cardiopulmonary function, whereas the T1data suggest similar environments for the anesthetic in young and o

ISSN:0952-3480    

DOI:10.1002/nbm.1940050304

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractA xenografted hypopharynx carcinoma growing subcutaneously in nude mice was studied byin vivo31P NMR spectroscopy during uninfluenced growth and following treatment with cisplatin (CDDP). Parallel to the NMR experiments, the cytokinetic and histological changes in the tumor were investigated. The most significant change in the growing tumor was a decline in the level of phosphocreatine (PCr), whereas the tumor pH did not change. Following treatment with CDDP (4, 8 and 12 mg/kg), a dose‐dependent decrease in the level of phosphomonoesters (PME) took place, whilst no dose dependence could be observed for the increase of PCr. the pH shifted to alkaline only after administration of the highest CDDP dose. Tumor cytokinetics revealed a cell arrest at the G1/S boundary 24 h after chemotherapy. At this time, the histological sections showed a dilatation of capillaries, whereas first necroses appeared on day 3. The proliferative activity of the tumor showed a sharp decline 24 h after CDDP application, followed by a revival of cell proliferation that was proportional to the dose applied between days 5 and 7. This increase in proliferative activity was paralleled by a marked increase in the PME/phosphodiesters ratio. Thus, in the tumor investigated the PME were the best indicators of tumor response to therapy. A precise correlation between the cytokinetic data and the re‐energization of the tumor was not possible because histological changes, which may contribute to improved tumor energy status took place at the same t

ISSN:0952-3480    

DOI:10.1002/nbm.1940050305

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractQuantification of metabolites is a goal of many biomedical NMR studies. To obtain absolute measurements of metabolite concentrations is often both difficult and time‐consuming. In this paper a method for determining metabolite concentrations directly is described and validated. It is applicable to studies of amphibian muscles, and with suitable precautions, to other isolated organs and tissues. The method is based upon using14N NMR and nitrate‐containing solutions to determine what fraction (F) of the sensitive volume of the RF coil is occupied by tissue. As the concentration of nitrate is known it can be used to calibrate other14N metabolites in the tissue. Moreover, once F is determined, it can be used to calibrate metabolites in spectra from other nuclei e.g.,31P or31C. All that is required is that a spectrum from a standard for that nucleus is obtained. Thus this method does not require any “internal” (intrinsic to the tissue) standard, and is extremely quick and simple

ISSN:0952-3480    

DOI:10.1002/nbm.1940050306

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractSpin inversion produced by hyperbolic secant RF pulses is independent of pulse amplitude once a threshold value is exceeded. A semi‐empirical formula for these pulses has been derived by application of analytical solutions to the Bloch equations. This predicts the required coil voltages for inversion as a function of inversion bandwidth and side‐to‐width parameter μ, based on knowledge of a reference voltage for the loaded coil. The voltage required is shown to increase linearly with bandwidth but to fall with the μ, approximately as (1/μ)0·4. Experimental confirmation is presented, and factors affecting choice of pulse parameters are

ISSN:0952-3480    

DOI:10.1002/nbm.1940050307

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractCerebral energy metabolism can be measured non‐invasively in unanesthetized neonatal rats with31P NMR spectroscopy. Using this technique, serial changes in high energy phosphates were determined from the right cerebral hemispheres of 7 day postnatal rat pups during a hypoxic‐ischemic insult known to produce focal brain injury. During 3 h of hypoxia‐ischemia the concentration of ATP dropped to 33±8% of prehypoxic (baseline) levels, phosphocreatine (PCr)/Pidecreased from 1.5±0.51 to 0.16±0.06, while pH decreased nominally by 0.2 units. After 2.5 h of recovery in air, ATP returned to 75±10% of baseline levels, PCr/Pirose to 1.1±0.28, and pH returned to its normal value of 7.16±0.06. This model was used to test the efficacy of the adenosine deaminase inhibitor, 2‐deoxycoformycin (DCF) as a potential neuroprotective drug. The data for the drug‐ and saline‐treated populations were analyzed by integrating ATP and Pi/PCr levels over specific time intervals, expressing it relative to baseline levels, and modeling it with cubic splines. Pretreatment with 500 μg/kg DCF shows a small, but statistically significant, preservation of both ATP and phosphorylation potential during hypoxia and initial recovery. Brain water content (edema) at 42 h recovery was apparently associated with both mean ATP and mean Pi/PCr in the last 2 h of hypoxia‐ischemia. When ATP fell below 70% of baseline, brain edema was evident at 42 h of recovery. This methodology is suitable for extens

ISSN:0952-3480    

DOI:10.1002/nbm.1940050308

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

摘要:

AbstractWe have used phase modulated rotating frame imaging, a depth selective NMR technique, in conjunction with two methods of calibration, in order to determine the feasibility of quantifying phosphorus compounds in selected regions of a biological sample. In one method, we related peak areas obtained from a sample to the peak area of an external reference located within the receiver coil, previously calibrated against a standard. In the second method we measured peak areas from a standard separately and related them directly to the area of the sample peak. We examined the calf muscles of male volunteers, positioning the coil to obtain signal mainly from the gastrocnemius in the shallow slices and soleus in the deep slices. The concentrations of Pi, phosphocreatine and ATP (in mmol/kg tissue) were 3.0±0.5, 18±2 and 4.8±0.2 at 2 cm depth (mean±SD;n= 5). These results are similar to published biopsy data. A comparison with published values obtained from other NMR quantification methods suggests that, while it is possible to obtain consistent results within one laboratory, it is not currently possible to obtain similar results between laboratories. This is evident from the fact that different laboratories report different phosphocreatine/ATP ratios, indicating that the techniques are limited by variations in the processes of data collection and peak area measurem

ISSN:0952-3480    

DOI:10.1002/nbm.1940050309

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY

ISSN:0952-3480    

DOI:10.1002/nbm.1940050301

出版商:John Wiley&Sons, Ltd.    

年代:1992

数据来源: WILEY